Microelectronics processing is a matter of surfaces. Processing techniques are concerned with modifying properties less than a few microns below or above the surface of a substrate material. Present complex electronic integrated circuits are formed by using planar processes in which an ultraclean, flat wafer of silicon is used as a substrate upon which a large number of identical devices are built by various oxidation, photolithography, removal, ion bombardment and deposition processes. Therefore, the integrated circuit manufacturing is essentially a sequence of chemical processes.
An ultraclean surface preparation before and after the processes necessary for the patterning of microelectronics devices is now more important than ever before as the surface diameter extends toward 300 mm. and the structure dimension shrink below microns. It is well known that the device performance, reliability and product yield of silicon circuits are critically affected by the presence of chemical contaminants and particulate impurities on the wafer of device surface.
Current existing methods for ultraclean surface preparation can be divided into two main categories: wet processes, such as immersion and spray techniques, and dry processes such as chemical vapor and plasma based techniques.
Wet processing consists of a series of steps of immersing or spraying the wafers with appropriate chemical solutions. The wet processes for ultraclean wafer surface preparation has been successfully used for the past twenty-five years and are still the predominant methods used in manufacturing circuits. However, the high cost of the large amount of ultrapure chemicals required in the current wet processes and the treatment of hazardous waste resulting from the processes, together with its incompatibility with the advanced concepts of integrated processing such as cluster tooling, are the main reason for searching for gas processing methods that are less affected by these limitations.
Although dry processing has shown several advantages in the chemical processing of advanced sub-micron features integrated circuits with high aspect ratio structures, numerous advantages of wet chemical processing often outweigh their "generic" problems in many production applications.
There is a real need in today's semiconductor fabrication industry to tailor the chemical processes to minimize the manufacturing costs in order to remain competitive in the ever increasing demands of the semiconductor market, while at the same time, to meet the increasing quality demands of the devices. The best answer for that is to combine the wet and dry techniques into the processes.
Thus, there is a need of a method and apparatus for the ultraclean surface preparation that is capable of performing both wet and dry chemical processes.
There is also a strong need for a method and apparatus to reduce chemical consumption, to reduce processing steps, and to increase equipment utilization without losing the effectiveness of the process.
There is further need for a method and a system that can be fully automated, well controlled, and integrated with cluster tool environments.